The present invention relates to methods and compositions for adding fertilizers and/or soil amendments to micro-irrigation systems.
The agriculture industry has developed the practice of adding plant nutrients and soil amendments to the plant environs, such as the soil, to enhance crop growth and subsequent yields. These fertilizers and amendments come in a variety of formulations depending on the specific crop to be grown and its nutrient requirements.
Fertilizers generally are classified according to their NPK content. NPK is common terminology used in the fertilizer industry and stands for: (1) N—the amount of nitrogen in the formulation as N; (2) P—the amount of phosphorus in the formulation as P2O5; and (3) K—the amount of potassium in the formulation as K2O.
Depending on the formulation of the fertilizer, the fertilizer can also act as a soil amendment, or soil amendment agent, which is a material that conditions the soil, particularly the structure of the soil. Typical soil amendment agents include minerals, such as gypsum and lime, and acids, such as sulfuric acid or urea-sulfuric acid mixtures. The benefits of these amendments include, without limitation: (1) soil structure improvement; (2) sodic soil reclamation; (3) soil crusting prevention (aids in seedling emergence); (4) compacted soil loosening; (5) nutrient absorption improvement; (6) water run-off and erosion prevention; and (7) subsoil pH adjustment (impacts nutrient availability for absorption).
Mankind learned to add these fertilizers/soil amendments centuries ago to grow better crops to feed the ever-increasing population. Initially, these materials were typical inorganic compounds that were mined by the local natives and simply added to the soil in which the crop was grown. As the population increased further, irrigation of the land to improve crops and crop yields became another common agricultural practice. Fertilization methods ultimately were facilitated by the practice of adding inorganic fertilizers and soil amendments to the water being used to irrigate the crops. The term “fertigation” is sometimes used for this combination of irrigation and fertilization. Although the early techniques were extremely crude by today's standards, the techniques nonetheless obtained better yields and drastically minimized the labor of applying these fertilizers.
Today's high demand for crops (food crops and otherwise) has turned agriculture into a technically-sophisticated business, and a business in which large corporate farms dominate the small family farm. The technical challenges faced by the modern agricultural industry include both the ever-increasing need for arable land, especially in the western and southwestern United States, and the decreasing availability and increasing cost of water. To meet the need for water conservation, today's technology includes micro-irrigation systems that deliver very precise amounts of water directly to the plant that is being grown. In the past 20 to 30 years a large percentage of crop producers in the western and southwestern United States have converted to irrigation systems utilizing this micro-irrigation technology.
Similar to the advent of “fertigation” practices generally, upon conversion to micro-irrigation systems, modern farmers began adding fertilizers and soil amendments to them. In micro-irrigation systems, unfortunately, water quality and the inclusion of fertilizers and other additives cause severe problems. The problems arise from a number of factors. (1) The micro-irrigation water is typically obtained from wells, reservoir, lakes, or rivers which contain various amounts of dissolved minerals. (2) Fertilizers, soil amendments and other additives can form insoluble salts and/or cause particulate formation when added to the water. Macro-irrigation systems mainly tolerate these conditions, while micro-irrigation systems are extremely intolerant.
The sensitivity of micro-irrigation systems to water quality and additives stems from the refinement of the components in a micro-irrigation system. In order to add precise amounts of water directly to the plant or crop being irrigated, micro-irrigation systems contain devices called emitters, micro-sprinklers or other such devices. These devices deliver the desired precise amounts of water so long as they do not plug or foul. Plugging occurs when deposits, from any source, build up inside these devices. The smallest particle or foreign material can cause fouling of these devices, because these devices have very tiny orifices and/or a long tortuous narrow passageway that provide the requisite pressure for delivery of precise amounts of water in a uniform manner to each plant in the crop being irrigated.
The addition of fertilizers or other materials, for instance soil amendments, to the micro-irrigation water increases the loading of inorganic salts over that already in the water. When the loading, or the combined loading, is too high, the solubilities of at least some of the naturally-occurring minerals and/or added compounds are exceeded and particulate formation increases dramatically. When particulates form, significant deposits begin to build up throughout the entire micro-irrigation system. The end result is plugging of the emitters or micro-sprinklers. Plugging results in uneven distribution of water and nutrients to the crop being irrigated. In some cases, complete shut-down of the irrigation system occurs. Therefore problem-free use of additives such as fertilizers and/or soil amendments and the like in micro-irrigation systems is conventionally limited to the systems that use relatively pure water sources. When the water source is not relatively pure, the fertilizer or soil amendment is often distributed to the crop by means other than through the irrigation system, with the loss of “fertigation” benefits.
It is an object of the invention to provide stable, non-plugging, concentrated fertilizer/amendment formulations that can be used in drip irrigation systems even though they are being added to irrigation systems using impure, naturally-occurring waters. The term “micro-irrigation” as used herein and in the claims refers to microsprinkers, drip, and subsurface drip systems. It is an object of the invention to provide affordable concentrated fertilizer/amendment solutions comprising cost-effective additives that act synergistically, stabilizing the naturally-occurring water and fertilizer/amendment matrix.
Another object of the invention is to provide mixtures or combinations of naturally-occurring water plus fertilizer/amendment formulations that are stable for prolonged periods of time. This is important since once an irrigation system is shut down and the fertilizer is not flushed from the irrigation system, plugging may happen over time since all the water does not drain out of the irrigation system. A further object of the invention is to provide fertilizer/amendment formulations that aid in modification of the soil such that plant nutrients are more readily available to the crop being irrigated. These and other objects of the invention will be seen below.